import { execFile } from 'node:child_process';
import { promisify } from 'node:util';
import type { GatherContext } from './types.ts';

const exec = promisify(execFile);

type SessionRepoSource = 'git-remote-origin' | 'none';

async function git(args: string[], cwd: string): Promise<string | null> {
  try {
    const { stdout } = await exec('git', args, {
      cwd,
      timeout: 1500,
      env: {
        ...process.env,
        GIT_TERMINAL_PROMPT: '0',
      },
    });
    const value = stdout.trim();
    return value.length > 0 ? value : null;
  } catch {
    return null;
  }
}

function stripGitSuffix(input: string): string {
  return input.replace(/\.git$/i, '');
}

export function parseGitHubRepoSlug(remoteUrl: string): string | null {
  const raw = remoteUrl.trim();
  if (!raw) return null;

  const scpLike = raw.match(/^git@github\.com:([^/\s]+)\/(.+)$/i);
  if (scpLike) {
    const owner = scpLike[1]?.trim();
    const repo = stripGitSuffix((scpLike[2] ?? '').trim().replace(/\/+$/, ''));
    if (!owner || !repo) return null;
    return `${owner.toLowerCase()}/${repo.toLowerCase()}`;
  }

  try {
    const url = new URL(raw);
    if (url.hostname.toLowerCase() !== 'github.com') return null;
    const parts = url.pathname.split('/').filter(Boolean);
    if (parts.length < 2) return null;

    const owner = parts[0]?.trim();
    const repo = stripGitSuffix((parts[1] ?? '').trim());
    if (!owner || !repo) return null;
    return `${owner.toLowerCase()}/${repo.toLowerCase()}`;
  } catch {
    return null;
  }
}

export async function resolveGatherContext(
  provider: string,
  cwd: string = process.cwd(),
): Promise<GatherContext> {
  const context: GatherContext = {
    provider,
    cwd,
    sessionRepoSource: 'none' as SessionRepoSource,
  };

  const gitRoot = await git(['rev-parse', '--show-toplevel'], cwd);
  if (gitRoot) {
    context.gitRoot = gitRoot;
    context.cwd = cwd;
  }

  const remote = await git(['config', '--get', 'remote.origin.url'], gitRoot ?? cwd);
  const sessionRepo = remote ? parseGitHubRepoSlug(remote) : null;
  if (sessionRepo) {
    context.sessionRepo = sessionRepo;
    context.sessionRepoSource = 'git-remote-origin' as SessionRepoSource;
  }

  return context;
}